Search

The ultrasound-guided cervical plexus plane (US-CPP) block has proven effective in humans; yet its application in dogs remains unexplored. This study aimed to describe a novel US-CPP approach in canines. A local sonoanatomy was mapped, the injection technique was tested, and a gross anatomical dissection (GAD) was performed on one cadaver. The bilateral injectate spread and nerve staining were then evaluated via a CT scan and GAD in the six cadavers. The transducer was aligned parallel to the cervical spine, caudal to the atlas. After identifying the cleidocervical and omotransversarius muscles and the C2-C3 interfascial plane, a spinal needle was inserted in-plane, and 0.15 mL/kg of a dye-contrast solution was injected. CT imaging showed the contrast reaching the C1, C2, and C3 vertebral bodies in 3 out of 12 (3/12), 11/12, and 12/12 injections, respectively, and the C4, C5, and C6 vertebrae in 8/12, 5/12, and 1/12 injections, respectively. No contrast was detected in the epidural space. The C1, C2, C3, C4, and C5 nerves were stained in 3/12, 10/12, 8/12, 2/12, and 0/12 injections, respectively. No significant differences were observed between the groups ( p > 0.05). A single US-CPP injection successfully stained the C2 and C3 nerves, indicating the potential clinical applicability, although the injected volume rarely reached C4 and C5.

This study assessed the analgesic and motor effects of the GIN-TONIC block, a combination of the greater ischiatic notch plane block and the caudal lateral quadratus lumborum block, in 24 dogs undergoing pelvic limb surgery. Dogs were randomly divided into two equal groups: G A received acepromazine [(20 µg kg -1 intravenously (IV)] as premedication, and G D received dexmedetomidine (2 µg kg -1 IV). General anesthesia was maintained with isoflurane, and both groups received a GIN-TONIC block using 2% lidocaine. Nociception during surgery and postoperative pain [assessed using the Glasgow Composite Measure Pain Score (GCMPS-SF)] were assessed. Fentanyl (2 µg kg -1 IV) was administered if nociception was noted and morphine (0.5 mg kg -1 IV) was administered during recovery if the pain scores exceeded the predefined threshold. Motor function was assessed during the recovery period using descriptors previously reported. All dogs received analgesics at the 4 h mark before being discharged. Three and two dogs in G D and G A required fentanyl once. Postoperative pain scores remained ≤4/20 for all dogs except one. Dogs achieved non-ataxic ambulation within 38.9 ± 10.3 and 35.1 ± 11.1 min after extubation in G D and G A , respectively. This study highlighted the potential of the GIN-TONIC block as a feasible regional anesthesia method for delivering perioperative analgesia in dogs undergoing pelvic limb orthopedic surgery.

The trigeminal nerve is responsible for innervating the periorbita. Ultrasound-guided trigeminal block is employed in humans for trigeminal neuralgia or periorbital surgery. There are no studies evaluating this block in dogs. This study aims to evaluate and compare two approaches (coronoid and temporal) of the trigeminal nerve block. We hypothesised superior staining with the coronoid approach. Thirteen dog heads were used. After a preliminary anatomical study, two ultrasound-guided injections per head (right and left, coronoid and temporal approach, randomly assigned), with an injectate volume of 0.15 mL cm -1 of cranial length, were performed (iodinated contrast and tissue dye mixture). The ultrasound probe was placed over the temporal region, visualising the pterygopalatine fossa. For the temporal approach, the needle was advanced from the medial aspect of the temporal region in a dorsoventral direction. For the coronoid approach, it was advanced ventral to the zygomatic arch in a lateromedial direction. CT scans and dissections were conducted to assess and compare the position of the needle, the spread of the injectate, and nerve staining. No significant differences were found. Both approaches demonstrated the effective interfascial distribution of the injectate, with some minimal intracranial spread. Although the coronoid approach did not yield superior staining as hypothesised, it presents a viable alternative to the temporal approach. Studies in live animals are warranted to evaluate clinical efficacy and safety.

This study aimed to evaluate the benefits of applying 5 cmH 2 O of CPAP using a pediatric helmet during the recovery phase from general anesthesia in brachycephalic dogs. Brachycephalic dogs undergoing various surgical procedures were included in this study, and a total of 64 subjects were randomly assigned to receive either standard oxygen supplementation (NO-CPAP group) or oxygen supplementation combined with CPAP (CPAP group). This study evaluated arterial blood pH, blood gas partial pressures of O 2 and CO 2 , arterial blood O 2 saturation, and related parameters during recovery. The dogs were monitored, and helmet tolerance was assessed using predefined criteria. Of the initially assessed 69 dogs, 64 were enrolled: 32 in the CPAP group and 32 in the NO-CPAP group. Fifteen dogs in the NO-CPAP group were excluded based on predetermined criteria. The CPAP group showed significant improvements in PaO 2 , PaO 2 /FiO 2 , P(A-a)O 2 , F-Shunt, and respiratory rate compared with the NO-CPAP group ( p < 0.001). The incidence of reintubation and helmet intolerance was higher in the NO-CPAP group (18% and 15.6%, respectively) than in the CPAP group (0%). This study highlights the potential benefits of incorporating CPAP, delivered through a pediatric helmet, in the perioperative management of brachycephalic dogs., Competing Interests: The authors declare no conflict of interest.

Background: Ultrasound-guided quadratus lumborum block (QLB) and sacrococcygeal epidural anaesthesia (ScE) have been used for neutering cats, providing effective pain relief., Objectives: To compare the effects of the QLB with those of ScE in cats undergoing ovariectomies., Methods: Feral cats undergoing ovariectomy were premedicated with dexmedetomidine (20 μg kg -1 ) and methadone (0.2 mg kg -1 ) intramuscularly. Anaesthesia was induced with 2-4 mg kg -1 of propofol intravenously and maintained with isoflurane in oxygen. The cats were randomly allocated to the groups QLB (bilateral QLB with 0.4 mL kg -1 of 0.25% bupivacaine) and ScE (0.3 mL kg -1 of 0.25% bupivacaine). Hemodynamic data and analgesia rescue were collected at four intraoperative periods. The pain scale and motor block were assessed in both groups during the postoperative period., Results: The ScE results in increased hypotension, prolonged extubation time, and higher postoperative motor block than the QLB ( p < 0.05). The QLB and ScE groups required a similar number of intraoperative rescues and presented the same postoperative pain scale classification., Conclusions: The QLB with 0.25% bupivacaine is a potential alternative to ScE with 0.25% bupivacaine in perioperative pain management in elective cat ovariectomy. The QLB promoted less hypotension and postoperative motor block when compared with the ScE group.

To evaluate the sensory and motor effects promoted by a combined sciatic and femoral nerve block in calves using two approaches. Six calves were used, in a crossover study. Ultrasound combined with neurostimulation, was used to perform the following block combinations: the proximal approach (PA), which consisted of the association of the parasacral approach (sciatic nerve block) and ventral to the ilium approach (femoral nerve block); distal approach (DA) consisted of the association of a lateral approach to the pelvic limb approach (sciatic nerve block), and an inguinal approach, underneath the femoral trigone (femoral nerve block). Pressure algometry and motor function of the limb where evaluated. Mechanical nociceptive threshold (MNT) increase, and ataxia duration means were 9.5 ± 0.7 kg and 10.4 ± 3.9 hr for PA and 10.4 ± 3.9 kg and 12.7 ± 1.9 hr for DA, respectively with no significant difference. There was no significant difference between MNT elevation time and the duration of ataxia using the same approach. The DA treatment showed significant MNT elevation in 72% of the tested regions, while the PA treatment showed an elevation in 100% regions tested. Topographic approaches closer to where the spinal nerves emerge produced a larger desensitised area., Competing Interests: None., (© 2023 The Authors. Published by Elsevier Ltd.)

Pharmacodynamic understanding of the different local anesthetic concentrations allows adapting their use to diverse clinical/surgical procedures, such as intraoperative and/or postoperative analgesia. A crossover study was performed, where 6 calves (5 male and 1 female), weighing 120 ± 28 Kg, were subjected to combined sciatic and femoral nerve block using three ropivacaine concentrations. The treatments were: R0.75, using 0.75% ropivacaine; R0.2, 0.2% ropivacaine; and R0.12%, 0.12% ropivacaine. All treatments were performed with ultrasound and neurostimulation assistance, and a volume of 0.1 mL/kg of the respective local anesthetic solution was administered in each block point. The sites of mechanical nociceptive threshold (MNT) evaluation were based on the calf pelvic limb dermatomes. The proportion between desensitized areas, MNT elevation time and level of ataxia were registered. Elevation of MNT occurred in 100% of the tested areas in the R0.75 and R0.2 treatments, and in 82% of the R0.12 treatment. Mean MNT elevation times were 9.5 ± 0.7 h for R0.75, 6 ± 0.8 for R.02, and 2.4 ± 2.3 for R0.12, differing significantly between all treatments. No difference was observed between MNT elevation time and ataxia duration time, in each treatment. It is concluded that the duration of sensory-motor effects is dose-dependent, but there was not possible to detect block selectivity as the concentrations was reduced. More desensitized areas and extension were obtained with the use of higher concentrations., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors. Published by Elsevier Ltd.)

Background: In medicine, the transversus abdominis plane (TAP) block has been shown as an effective method of analgesia in several surgical procedures. In this context, this prospective, randomized, blinded study aimed to evaluate the analgesic efficacy of TAP block, guided by ultrasound in female dogs submitted to ovariectomy., Methods: Therefore, 32 animals randomly assigned in two groups ( n = 16) were used. Groups consisted of TAP block control (TBC) which received water injection (0.2 ml kg -1 point), and TAP block bupivacaine (TBB) which received bupivacaine (0.2 ml kg -1 point at 0.25%); both groups were submitted to four-point approach. Animals were pre-medicated with acepromazine (0.03 mg kg -1 ) and meperidine (2 mg kg -1 ) IM, propofol was used as anesthetic induction (3-5 mg kg -1 ) IV, and isoflurane was used to maintain. To standardize groups, the animals received a continuous infusion of remifentanil (0.2μg kg -1 min) and rocuronium (0.6 mg kg -1 ) IV in the intraoperative period. Variables measured were the heart and respiratory rates, blood pressure, temperature, peripheral oxyhemoglobin saturation, exhaled carbon dioxide concentration, exhaled isoflurane concentration, serum cortisol, analgesia, and sedation. Before the pre-anesthetic medication (Baseline) and 1, 2, 4, 6, and 8 h after extubation, pain and sedation were assessed using a numeric rating scale (NRS), Glasgow composite measure pain scale (GCMPS-SF), and sedation scale. Moreover, serum cortisol was measured at different moments., Results: The results show that in the intraoperative period, there was no significant difference between groups. After surgery, in TBC, 13 out of 16 animals required analgesic rescue, whereas, in TBB, this occurred only in one animal. Regarding the measurement of serum cortisol, the TBC group showed a significant difference when compared to the baseline time in the traction of the first ovary ( p < 0.0001), 2 h ( p = 0.0441), and 8 h ( p = 0.0384) after extubation. In TBB, cortisol showed a significant increase only in the traction of the first ovary and 2 h after extubation ( p < 0.0001)., Conclusion: The technique using ultrasound-guided TAP block in two points approach by hemiabdomen with 0.2 ml kg -1 bupivacaine 0.25% was effective in providing post-operative analgesia in dogs undergoing ovariectomy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Cavaco, Otero, Ambrósio, Neves, Perencin, Pereira, Matera and Fantoni.)

Background: To analyze the role of PEEP on dynamic relative regional strain (DRRS) in a model of ARDS, respective maps were generated by electrical impedance tomography (EIT)., Methods: Eight ARDS pigs submitted to PEEP steps of 0, 5, 10, and 15 cm H 2 O at fixed ventilation were evaluated by EIT images. DRRS was calculated as (V T-EIT /EELI)/(V T-EIT[15PEEP] /EELI [15PEEP] ), where the tidal volume (V T ) -EIT and end-expiratory lung impedance (EELI) are the tidal and end-expiratory change in lung impedance, respectively. The measurement at 15 PEEP was taken as reference (end-expiratory transpulmonary pressure > 0 cm H 2 O). The relationship between EIT variables (center of ventilation, EELI, and DRRS) and airway pressures was assessed with mixed-effects models using EIT measurements as dependent variables and PEEP as fixed-effect variable., Results: At constant ventilation, respiratory compliance increased progressively with PEEP (lowest value at zero PEEP 10 ± 3 mL/cm H 2 O and highest value at 15 PEEP 16 ± 6 mL/cm H 2 O; P < .001), whereas driving pressure decreased with PEEP (highest value at zero PEEP 34 ± 6 cm H 2 O and lowest value at 15 PEEP 21 ± 4 cm H 2 O; P < .001). The mixed-effect regression models showed that the center of ventilation moved to dorsal lung areas with a slope of 1.81 (1.44-2.18) % points by each cm H 2 O of PEEP; P < .001. EELI increased with a slope of 0.05 (0.02-0.07) (arbitrary units) for each cm H 2 O of PEEP; P < .001. DRRS maps showed that local strain in ventral lung areas decreased with a slope of -0.02 (-0.24 to 0.15) with each cm H 2 O increase of PEEP; P < .001., Conclusions: EIT-derived DRRS maps showed high strain in ventral lung zones at low levels of PEEP. The findings suggest overdistention of the baby lung., Competing Interests: Dr Tusman wrote a patent regarding electrical impedance tomography and lung strain. Dr Madorno is partner and manager of MBMed SA. Mr Gogniat is currently employed by Medtronic Argentina. The remaining authors have disclosed no conflicts of interest., (Copyright © 2022 by Daedalus Enterprises.)

The use of transthoracic echocardiography (TTE) and esophageal Doppler (ED) for the measurement of hemodynamic variables in anesthetized dogs was studied. Fourteen mixed-breed dogs, without cardiac disease, undergoing general anesthesia for diagnostic or therapeutic procedures were included in this prospective preliminary study. Dogs were premedicated with dexmedetomidine (3 μg/kg) and methadone (0.3 mg/kg), intramuscularly. General anesthesia was induced with propofol intravenously titrated to effect and maintained with isoflurane in oxygen. Animals were positioned in dorsal recumbency. Transthoracic echocardiography was performed using a 5-2 MHz cardiac ultrasound probe placed in the subcostal window, whereas esophageal Doppler was performed using a CardioQ probe (MP50; Deltex Medical, Chichester, UK). Once an appropriate view of the aortic flow was obtained, the variables peak velocity (PV) and velocity-time integral (VTI) were measured. Agreement between methods was evaluated using the Bland-Altman method with single observation per individual. The bias and the limits of agreement (LOA) between the two methods were determined. Mean (± SD) PV was 99.46 cm/s (± 42.73 cm/s) and 110.29 cm/s (± 35.86 cm/s), and VTI was 13.24 cm (± 4.33 cm) and 13.05 cm (± 4.47 cm), for TTE and ED, respectively. Mean differences and LOA were 10.83 cm/s (range: -20.50 to 42.16 cm/s) and -0.19 cm (range: -3.32 to 2.95 cm) for PV and VTI, respectively. No statistically significant differences were determined in the variables measured between TTE and ED in anesthetized dogs without cardiac disease, positioned in dorsal recumbency. This could be of clinical relevance when an evaluation of the intraoperative hemodynamic status of anesthetized dogs is desired., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

Objectives: The aim of this study was to determine the occurrence of dural puncture, indicated by cerebrospinal fluid (CSF) outflow, in cats receiving neuraxial anesthesia through a lumbosacral injection guided by a pop sensation method., Methods: This was an observational, retrospective study. Cats that were scheduled for lumbosacral neuraxial anesthesia were included. Medical records were analyzed to investigate: (1) demographic data; (2) neuraxial anesthesia performed (epidural/spinal); (3) type of needle used, including gauge and length; (4) presence of CSF (yes/no) and/or blood (yes/no) in the hub of the needle; and (5) flicking of the tail during needle advancement (yes/no)., Results: A total of 94 medical records were analyzed. A 22 G 50 mm Tuohy needle was used in all cats scheduled for an epidural injection (n = 60), whereas a 22 G 40 mm Quincke needle was used in all cats scheduled for an intrathecal injection (n = 34). CSF outflow was detected in 55/60 (91.7%) cats in which a Tuohy needle was used, and 34/34 (100%) of the cats in which a Quincke needle was used ( P  = 0.15). Flicking of the tail was detected in 41/60 (68.3%) and in 24/34 (70.6%) injections with Tuohy and Quincke needles, respectively ( P >0.99). Traces of blood, but not active blood outflow, were detected via staining of the first drops of CSF in 2/34 cats in which Quincke needles were used and in none of the cats in which Tuohy needles were used ( P  = 0.12)., Conclusions and Relevance: This study shows that the lumbosacral approach for neuraxial anesthesia in cats may result in a dural sac puncture when 22 G Quincke or Tuohy needles are used. The pop sensation method should be deemed effective in predicting intrathecal but not epidural needle placement.

A prospective, randomized clinical trial was designed to compare four epidural treatments in dogs undergoing total unilateral mastectomy. The epidural volume of injectate was based on the individual occipito-coccygeal length (OCL) aiming to reach the first thoracic vertebra (T1). The first ten dogs were allocated in a control group (C) and did not receive epidural treatment. Subsequently, forty dogs were randomly allocated in four groups of ten: epidural ropivacaine 0.5% (R0.5%); morphine 0.1 mg kg−1 plus ropivacaine 0.5% (MR0.5%); morphine 0.1 mg kg−1 plus ropivacaine 0.35% (MR0.35%); morphine 0.1 mg kg−1 plus ropivacaine 0.25% (MR0.25%). Intraoperatively, isoflurane requirement (1.3% vs. <1.1% FE’Iso) and fentanyl requirement (9.8 vs. <1.1 µg kg−1 h−1) were significantly higher in C group compared to all epidural groups. Postoperatively, methadone requirement was higher (1.8 mg kg−1 vs. <0.8 mg kg−1) for C group compared to all epidural treatment groups. The ability to walk and to urinate returned 4 h earlier in MR0.35% and MR0.25%. The mean epidural volume of ropivacaine, using a dose regimen based on OCL, to reach T1 was about 0.15 mL cm−1. The addition of morphine further reduced the methadone requirement, without affecting urinary and motor functions.

The current COVID-19 pandemic has led the world to an unprecedented global shortage of ventilators, and its sharing has been proposed as an alternative to meet the surge. This study outlines the performance of a preformed novel interface called 'ACRA', designed to split ventilator outflow into two breathing systems. The 'ACRA' interface was built using medical use approved components. It consists of four unidirectional valves, two adjustable flow-restrictor valves placed on the inspiratory limbs of each unit, and one adjustable PEEP valve placed on the expiratory limb of the unit that would require a greater PEEP. The interface was interposed between a ventilator and two lung units (phase I), two breathing simulators (phase II) and two live pigs with heterogeneous lung conditions (phase III). The interface and ventilator adjustments tested the ability to regulate individual pressures and the resulting tidal volumes. Data were analyzed using Friedman and Wilcoxon tests test (p < 0.05). Ventilator outflow splitting, independent pressure adjustments and individual tidal volume monitoring were feasible in all phases. In all experimental measurements, dual ventilation allowed for individual and tight adjustments of the pressure, and thus volume delivered to each paired lung unit without affecting the other unit's ventilation-all the modifications performed on the ventilator equally affected both paired lung units. Although only suggested during a dire crisis, this experiment supports dual ventilation as an alternative worth to be considered., Competing Interests: The authors have declared that no competing interests exist.

Desensitizing the femoral nerve (FN) improves pain control in several species undergoing pelvic limb surgeries. Despite its advantages, this method has not yet been described in pigs, although they make an accepted surgical animal model. Based on anatomical dissections, first performed in two pig cadavers, an ultrasound-guided access for localization and perineural infiltration of the FN trunk at the iliopsoas compartment level was specified. The FN was found running between the psoas major and medial portion of iliac muscle. Ultrasonographically, the FN appeared as a hypoechogenic round-oval structure surrounded by a hyperechogenic rim. Technical feasibility and accuracy were assessed in six additional pig cadavers by injecting 0.15 mL kg -1 methylene blue dye bilaterally in direct proximity to the nerve. The needle was inserted caudoventral to the coxal tuber, traversing the ultrasound plane as it progressed towards the FN in dorsomedial direction. Staining of the nerve was evaluated by dissection. The injection was considered effective if the nerve was stained in its entire circumference over a length of 2 cm. FNs of all investigated individuals could be successfully stained. This ultrasound-guided subiliac approach allows feasible and accurate access to the FN and may be useful in producing a successful blockade in vivo.

Transversus abdominis plane (TAP) block is a regional anesthetic technique used to desensitize the abdominal wall in several species. This study aimed to describe the anatomical characteristics of the abdominal wall and to identify a feasible approach for an US-guided TAP injection that would result in adequate staining of the relevant nerves in the abdominal wall in pig cadavers. Fresh cadavers from five Landrace pigs (age, 12 weeks; body weight, 35.5 ± 1.6 kg) were used. One pig (n = 1) was anatomically dissected, and four pigs (n = 4; i.e., 8 hemiabdomens) were used for TAP injections and evaluation of dye spread. The volume of 0.3 mL/kg/injection point of methylene blue was injected bilaterally. In the caudal retrocostal approach, the injection was performed ventral to the most caudal part of the costal arch. In the lateral approach, the injection was performed between the last rib and iliac crest. A needle was inserted in plane for the caudal retrocostal and the lateral approach caudocranially and craniocaudally, respectively. Successful staining was defined as presence of dye on the nerve for a length of >1 cm in its entire circumference. The TAP was found between different muscle layers in the described anatomical regions. In the caudal retrocostal approach the TAP was found between the external abdominal oblique and transversus abdominis muscle bellies. In the lateral approach the TAP was found between the internal abdominal oblique and transversus abdominis muscles. The approach combining lateral and caudal retrocostal injections at the studied volume stained a median of 5 (3-6) target nerves from the fourth-last thoracic nerve to L2 (six nerves). Combined caudal retrocostal and lateral TAP injections of 0.3 mL/kg/injection point, resulted in staining of target nerve branches which supply the periumbilical and caudal abdominal wall in pig cadavers., Competing Interests: The authors have declared that no competing interests exist.

The purpose of this study was to compare cardiovascular and respiratory effects of two volumes of bupivacaine 0.25% (0.2 mL kg-1-treatment BUP02-and 0.4 mL kg-1 -treatment BUP04) administered epidurally at the lumbosacral intervertebral space in dogs anesthetized with isoflurane. This experimental prospective randomized crossover design trial used six mixed breed adult dogs, four neutered males and two spayed females. Each dog was anesthetized on three different occasions: the first for isoflurane minimum alveolar concentration (MAC) measurement, and the following two assigned treatments (BUP02 or BUP04). On the two treatment days, anesthesia was induced and maintained with isoflurane at 1.3 MAC during the experiments. Cardiovascular and respiratory measurements were recorded before (T0) and 5, 15, 30, 60 and 90 minutes after the epidural administration of bupivacaine. Comparisons between and within groups were performed by a mixed-model ANOVA and Friedman's test when appropriate followed by Bonferroni post-hoc test or Dunnet's test to compare time points within each treatment with T0 (p < 0.05). Mean arterial pressure decreased significantly from 15 to 90 minutes after the administration of BUP02 and from 5 to 60 minutes in BUP04, with lower values in BUP04 than in BUP02 lasting up to 30 minutes after bupivacaine administration. No significant changes in cardiac output and systemic vascular resistance were observed in either treatment. Hypoventilation was only detected in BUP04. Hemoglobin concentration and arterial oxygen content decreased after both treatment of bupivacaine with no significant decrease in oxygen delivery. Two dogs in BUP04 developed Horner's syndrome. The epidural administration of 0.4 mL.kg-1 of bupivacaine to dogs in sternal recumbency anesthetized with isoflurane 1.3 MAC caused more cardiovascular and respiratory depression than 0.2 mL.kg-1.

Objective: To determine the minimal electric threshold of neurostimulation dorsally and ventrally to the interarcuate ligament in the lumbosacral area necessary to cause muscle contraction of the hind limb or tail and determine whether a continuous electrical stimulation applied to an insulated needle during lumbosacral epidural needle placement could be used to distinguish the epidural from the intrathecal space in rabbits., Animals: 24 New Zealand white rabbits., Procedures: Rabbits received iohexol (0.2 mL/kg) either dorsally (group 1) or ventrally to the interarcuate ligament in the lumbosacral area (groups 2 and 3). Correct placement of the needle was determined by use of the loss of resistance to injection technique (group 2) or a continuous electrical stimulation (group 3) and confirmed by examination of the iohexol distribution pattern on radiographs., Results: In all rabbits of group 1, iohexol was injected in the lumbosacral area, outside the epidural space. In groups 2 and 3, iohexol was injected intrathecally. No pure iohexol epidural migration of iohexol was observed. Mean ± SD minimal electric threshold to elicit a motor response was 1.2 ± 0.3 mA, 0.3 ± 0.1 mA, and 0.3 ± 0.1 mA in groups 1, 2, and 3, respectively., Conclusions and Clinical Relevance: Neurostimulation was a useful technique to determine correct intrathecal needle placement in rabbits but failed to detect the lumbosacral epidural space when the common technique, used in dogs and cats for the lumbosacral epidural approach, was used.